4 * Maintainer: Jason Wessel <jason.wessel@windriver.com>
6 * Copyright (C) 2000-2001 VERITAS Software Corporation.
7 * Copyright (C) 2002-2004 Timesys Corporation
8 * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
9 * Copyright (C) 2004 Pavel Machek <pavel@ucw.cz>
10 * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
11 * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
12 * Copyright (C) 2005-2009 Wind River Systems, Inc.
13 * Copyright (C) 2007 MontaVista Software, Inc.
14 * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
16 * Contributors at various stages not listed above:
17 * Jason Wessel ( jason.wessel@windriver.com )
18 * George Anzinger <george@mvista.com>
19 * Anurekh Saxena (anurekh.saxena@timesys.com)
20 * Lake Stevens Instrument Division (Glenn Engel)
21 * Jim Kingdon, Cygnus Support.
23 * Original KGDB stub: David Grothe <dave@gcom.com>,
24 * Tigran Aivazian <tigran@sco.com>
26 * This file is licensed under the terms of the GNU General Public License
27 * version 2. This program is licensed "as is" without any warranty of any
28 * kind, whether express or implied.
30 #include <linux/pid_namespace.h>
31 #include <linux/clocksource.h>
32 #include <linux/interrupt.h>
33 #include <linux/spinlock.h>
34 #include <linux/console.h>
35 #include <linux/threads.h>
36 #include <linux/uaccess.h>
37 #include <linux/kernel.h>
38 #include <linux/module.h>
39 #include <linux/ptrace.h>
40 #include <linux/string.h>
41 #include <linux/delay.h>
42 #include <linux/sched.h>
43 #include <linux/sysrq.h>
44 #include <linux/reboot.h>
45 #include <linux/init.h>
46 #include <linux/kgdb.h>
47 #include <linux/kdb.h>
48 #include <linux/pid.h>
49 #include <linux/smp.h>
51 #include <linux/rcupdate.h>
53 #include <asm/cacheflush.h>
54 #include <asm/byteorder.h>
55 #include <linux/atomic.h>
56 #include <asm/system.h>
58 #include "debug_core.h"
60 static int kgdb_break_asap;
62 struct debuggerinfo_struct kgdb_info[NR_CPUS];
65 * kgdb_connected - Is a host GDB connected to us?
68 EXPORT_SYMBOL_GPL(kgdb_connected);
70 /* All the KGDB handlers are installed */
71 int kgdb_io_module_registered;
73 /* Guard for recursive entry */
74 static int exception_level;
76 struct kgdb_io *dbg_io_ops;
77 static DEFINE_SPINLOCK(kgdb_registration_lock);
79 /* Action for the reboot notifiter, a global allow kdb to change it */
80 static int kgdbreboot;
81 /* kgdb console driver is loaded */
82 static int kgdb_con_registered;
83 /* determine if kgdb console output should be used */
84 static int kgdb_use_con;
85 /* Flag for alternate operations for early debugging */
86 bool dbg_is_early = true;
87 /* Next cpu to become the master debug core */
90 /* Use kdb or gdbserver mode */
93 static int __init opt_kgdb_con(char *str)
99 early_param("kgdbcon", opt_kgdb_con);
101 module_param(kgdb_use_con, int, 0644);
102 module_param(kgdbreboot, int, 0644);
105 * Holds information about breakpoints in a kernel. These breakpoints are
106 * added and removed by gdb.
108 static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = {
109 [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
113 * The CPU# of the active CPU, or -1 if none:
115 atomic_t kgdb_active = ATOMIC_INIT(-1);
116 EXPORT_SYMBOL_GPL(kgdb_active);
117 static DEFINE_RAW_SPINLOCK(dbg_master_lock);
118 static DEFINE_RAW_SPINLOCK(dbg_slave_lock);
121 * We use NR_CPUs not PERCPU, in case kgdb is used to debug early
122 * bootup code (which might not have percpu set up yet):
124 static atomic_t masters_in_kgdb;
125 static atomic_t slaves_in_kgdb;
126 static atomic_t kgdb_break_tasklet_var;
127 atomic_t kgdb_setting_breakpoint;
129 struct task_struct *kgdb_usethread;
130 struct task_struct *kgdb_contthread;
132 int kgdb_single_step;
133 static pid_t kgdb_sstep_pid;
135 /* to keep track of the CPU which is doing the single stepping*/
136 atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1);
139 * If you are debugging a problem where roundup (the collection of
140 * all other CPUs) is a problem [this should be extremely rare],
141 * then use the nokgdbroundup option to avoid roundup. In that case
142 * the other CPUs might interfere with your debugging context, so
143 * use this with care:
145 static int kgdb_do_roundup = 1;
147 static int __init opt_nokgdbroundup(char *str)
154 early_param("nokgdbroundup", opt_nokgdbroundup);
157 * Finally, some KGDB code :-)
161 * Weak aliases for breakpoint management,
162 * can be overriden by architectures when needed:
164 int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr)
168 err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE);
172 return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr,
176 int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle)
178 return probe_kernel_write((char *)addr,
179 (char *)bundle, BREAK_INSTR_SIZE);
182 int __weak kgdb_validate_break_address(unsigned long addr)
184 char tmp_variable[BREAK_INSTR_SIZE];
186 /* Validate setting the breakpoint and then removing it. In the
187 * remove fails, the kernel needs to emit a bad message because we
188 * are deep trouble not being able to put things back the way we
191 err = kgdb_arch_set_breakpoint(addr, tmp_variable);
194 err = kgdb_arch_remove_breakpoint(addr, tmp_variable);
196 printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
197 "memory destroyed at: %lx", addr);
201 unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
203 return instruction_pointer(regs);
206 int __weak kgdb_arch_init(void)
211 int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
217 * Some architectures need cache flushes when we set/clear a
220 static void kgdb_flush_swbreak_addr(unsigned long addr)
222 if (!CACHE_FLUSH_IS_SAFE)
225 if (current->mm && current->mm->mmap_cache) {
226 flush_cache_range(current->mm->mmap_cache,
227 addr, addr + BREAK_INSTR_SIZE);
229 /* Force flush instruction cache if it was outside the mm */
230 flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
234 * SW breakpoint management:
236 int dbg_activate_sw_breakpoints(void)
243 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
244 if (kgdb_break[i].state != BP_SET)
247 addr = kgdb_break[i].bpt_addr;
248 error = kgdb_arch_set_breakpoint(addr,
249 kgdb_break[i].saved_instr);
252 printk(KERN_INFO "KGDB: BP install failed: %lx", addr);
256 kgdb_flush_swbreak_addr(addr);
257 kgdb_break[i].state = BP_ACTIVE;
262 int dbg_set_sw_break(unsigned long addr)
264 int err = kgdb_validate_break_address(addr);
271 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
272 if ((kgdb_break[i].state == BP_SET) &&
273 (kgdb_break[i].bpt_addr == addr))
276 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
277 if (kgdb_break[i].state == BP_REMOVED &&
278 kgdb_break[i].bpt_addr == addr) {
285 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
286 if (kgdb_break[i].state == BP_UNDEFINED) {
296 kgdb_break[breakno].state = BP_SET;
297 kgdb_break[breakno].type = BP_BREAKPOINT;
298 kgdb_break[breakno].bpt_addr = addr;
303 int dbg_deactivate_sw_breakpoints(void)
310 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
311 if (kgdb_break[i].state != BP_ACTIVE)
313 addr = kgdb_break[i].bpt_addr;
314 error = kgdb_arch_remove_breakpoint(addr,
315 kgdb_break[i].saved_instr);
317 printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr);
321 kgdb_flush_swbreak_addr(addr);
322 kgdb_break[i].state = BP_SET;
327 int dbg_remove_sw_break(unsigned long addr)
331 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
332 if ((kgdb_break[i].state == BP_SET) &&
333 (kgdb_break[i].bpt_addr == addr)) {
334 kgdb_break[i].state = BP_REMOVED;
341 int kgdb_isremovedbreak(unsigned long addr)
345 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
346 if ((kgdb_break[i].state == BP_REMOVED) &&
347 (kgdb_break[i].bpt_addr == addr))
353 int dbg_remove_all_break(void)
359 /* Clear memory breakpoints. */
360 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
361 if (kgdb_break[i].state != BP_ACTIVE)
363 addr = kgdb_break[i].bpt_addr;
364 error = kgdb_arch_remove_breakpoint(addr,
365 kgdb_break[i].saved_instr);
367 printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
370 kgdb_break[i].state = BP_UNDEFINED;
373 /* Clear hardware breakpoints. */
374 if (arch_kgdb_ops.remove_all_hw_break)
375 arch_kgdb_ops.remove_all_hw_break();
381 * Return true if there is a valid kgdb I/O module. Also if no
382 * debugger is attached a message can be printed to the console about
383 * waiting for the debugger to attach.
385 * The print_wait argument is only to be true when called from inside
386 * the core kgdb_handle_exception, because it will wait for the
387 * debugger to attach.
389 static int kgdb_io_ready(int print_wait)
395 if (atomic_read(&kgdb_setting_breakpoint))
398 #ifdef CONFIG_KGDB_KDB
400 printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n");
402 printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
408 static int kgdb_reenter_check(struct kgdb_state *ks)
412 if (atomic_read(&kgdb_active) != raw_smp_processor_id())
415 /* Panic on recursive debugger calls: */
417 addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
418 dbg_deactivate_sw_breakpoints();
421 * If the break point removed ok at the place exception
422 * occurred, try to recover and print a warning to the end
423 * user because the user planted a breakpoint in a place that
424 * KGDB needs in order to function.
426 if (dbg_remove_sw_break(addr) == 0) {
428 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
429 dbg_activate_sw_breakpoints();
430 printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
436 dbg_remove_all_break();
437 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
439 if (exception_level > 1) {
441 panic("Recursive entry to debugger");
444 printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
445 #ifdef CONFIG_KGDB_KDB
446 /* Allow kdb to debug itself one level */
450 panic("Recursive entry to debugger");
455 static void dbg_touch_watchdogs(void)
457 touch_softlockup_watchdog_sync();
458 clocksource_touch_watchdog();
459 rcu_cpu_stall_reset();
462 static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs,
466 int sstep_tries = 100;
470 int online_cpus = num_online_cpus();
472 kgdb_info[ks->cpu].enter_kgdb++;
473 kgdb_info[ks->cpu].exception_state |= exception_state;
475 if (exception_state == DCPU_WANT_MASTER)
476 atomic_inc(&masters_in_kgdb);
478 atomic_inc(&slaves_in_kgdb);
480 if (arch_kgdb_ops.disable_hw_break)
481 arch_kgdb_ops.disable_hw_break(regs);
485 * Interrupts will be restored by the 'trap return' code, except when
488 local_irq_save(flags);
491 kgdb_info[cpu].debuggerinfo = regs;
492 kgdb_info[cpu].task = current;
493 kgdb_info[cpu].ret_state = 0;
494 kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT;
496 /* Make sure the above info reaches the primary CPU */
499 if (exception_level == 1) {
500 if (raw_spin_trylock(&dbg_master_lock))
501 atomic_xchg(&kgdb_active, cpu);
502 goto cpu_master_loop;
506 * CPU will loop if it is a slave or request to become a kgdb
507 * master cpu and acquire the kgdb_active lock:
511 if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) {
512 kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER;
513 goto cpu_master_loop;
514 } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) {
515 if (raw_spin_trylock(&dbg_master_lock)) {
516 atomic_xchg(&kgdb_active, cpu);
519 } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) {
520 if (!raw_spin_is_locked(&dbg_slave_lock))
524 /* Return to normal operation by executing any
525 * hw breakpoint fixup.
527 if (arch_kgdb_ops.correct_hw_break)
528 arch_kgdb_ops.correct_hw_break();
531 kgdb_info[cpu].exception_state &=
532 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
533 kgdb_info[cpu].enter_kgdb--;
534 smp_mb__before_atomic_dec();
535 atomic_dec(&slaves_in_kgdb);
536 dbg_touch_watchdogs();
537 local_irq_restore(flags);
544 * For single stepping, try to only enter on the processor
545 * that was single stepping. To guard against a deadlock, the
546 * kernel will only try for the value of sstep_tries before
547 * giving up and continuing on.
549 if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
550 (kgdb_info[cpu].task &&
551 kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
552 atomic_set(&kgdb_active, -1);
553 raw_spin_unlock(&dbg_master_lock);
554 dbg_touch_watchdogs();
555 local_irq_restore(flags);
560 if (!kgdb_io_ready(1)) {
561 kgdb_info[cpu].ret_state = 1;
562 goto kgdb_restore; /* No I/O connection, resume the system */
566 * Don't enter if we have hit a removed breakpoint.
568 if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
571 /* Call the I/O driver's pre_exception routine */
572 if (dbg_io_ops->pre_exception)
573 dbg_io_ops->pre_exception();
576 * Get the passive CPU lock which will hold all the non-primary
577 * CPU in a spin state while the debugger is active
579 if (!kgdb_single_step)
580 raw_spin_lock(&dbg_slave_lock);
583 /* Signal the other CPUs to enter kgdb_wait() */
584 if ((!kgdb_single_step) && kgdb_do_roundup)
585 kgdb_roundup_cpus(flags);
589 * Wait for the other CPUs to be notified and be waiting for us:
591 while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) +
592 atomic_read(&slaves_in_kgdb)) != online_cpus)
596 * At this point the primary processor is completely
597 * in the debugger and all secondary CPUs are quiescent
599 dbg_deactivate_sw_breakpoints();
600 kgdb_single_step = 0;
601 kgdb_contthread = current;
603 trace_on = tracing_is_on();
611 error = kdb_stub(ks);
616 error = gdb_serial_stub(ks);
619 if (error == DBG_PASS_EVENT) {
620 dbg_kdb_mode = !dbg_kdb_mode;
621 } else if (error == DBG_SWITCH_CPU_EVENT) {
622 kgdb_info[dbg_switch_cpu].exception_state |=
626 kgdb_info[cpu].ret_state = error;
631 /* Call the I/O driver's post_exception routine */
632 if (dbg_io_ops->post_exception)
633 dbg_io_ops->post_exception();
635 if (!kgdb_single_step) {
636 raw_spin_unlock(&dbg_slave_lock);
637 /* Wait till all the CPUs have quit from the debugger. */
638 while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb))
643 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
644 int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step);
645 if (kgdb_info[sstep_cpu].task)
646 kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid;
650 if (arch_kgdb_ops.correct_hw_break)
651 arch_kgdb_ops.correct_hw_break();
655 kgdb_info[cpu].exception_state &=
656 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
657 kgdb_info[cpu].enter_kgdb--;
658 smp_mb__before_atomic_dec();
659 atomic_dec(&masters_in_kgdb);
660 /* Free kgdb_active */
661 atomic_set(&kgdb_active, -1);
662 raw_spin_unlock(&dbg_master_lock);
663 dbg_touch_watchdogs();
664 local_irq_restore(flags);
666 return kgdb_info[cpu].ret_state;
670 * kgdb_handle_exception() - main entry point from a kernel exception
673 * interface locks, if any (begin_session)
674 * kgdb lock (kgdb_active)
677 kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
679 struct kgdb_state kgdb_var;
680 struct kgdb_state *ks = &kgdb_var;
682 ks->cpu = raw_smp_processor_id();
683 ks->ex_vector = evector;
685 ks->err_code = ecode;
686 ks->kgdb_usethreadid = 0;
687 ks->linux_regs = regs;
689 if (kgdb_reenter_check(ks))
690 return 0; /* Ouch, double exception ! */
691 if (kgdb_info[ks->cpu].enter_kgdb != 0)
694 return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
697 int kgdb_nmicallback(int cpu, void *regs)
700 struct kgdb_state kgdb_var;
701 struct kgdb_state *ks = &kgdb_var;
703 memset(ks, 0, sizeof(struct kgdb_state));
705 ks->linux_regs = regs;
707 if (kgdb_info[ks->cpu].enter_kgdb == 0 &&
708 raw_spin_is_locked(&dbg_master_lock)) {
709 kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE);
716 static void kgdb_console_write(struct console *co, const char *s,
721 /* If we're debugging, or KGDB has not connected, don't try
723 if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode)
726 local_irq_save(flags);
727 gdbstub_msg_write(s, count);
728 local_irq_restore(flags);
731 static struct console kgdbcons = {
733 .write = kgdb_console_write,
734 .flags = CON_PRINTBUFFER | CON_ENABLED,
738 #ifdef CONFIG_MAGIC_SYSRQ
739 static void sysrq_handle_dbg(int key)
742 printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
745 if (!kgdb_connected) {
746 #ifdef CONFIG_KGDB_KDB
748 printk(KERN_CRIT "KGDB or $3#33 for KDB\n");
750 printk(KERN_CRIT "Entering KGDB\n");
757 static struct sysrq_key_op sysrq_dbg_op = {
758 .handler = sysrq_handle_dbg,
759 .help_msg = "debug(G)",
760 .action_msg = "DEBUG",
764 static int kgdb_panic_event(struct notifier_block *self,
769 kdb_printf("PANIC: %s\n", (char *)data);
774 static struct notifier_block kgdb_panic_event_nb = {
775 .notifier_call = kgdb_panic_event,
779 void __weak kgdb_arch_late(void)
783 void __init dbg_late_init(void)
785 dbg_is_early = false;
786 if (kgdb_io_module_registered)
788 kdb_init(KDB_INIT_FULL);
792 dbg_notify_reboot(struct notifier_block *this, unsigned long code, void *x)
795 * Take the following action on reboot notify depending on value:
796 * 1 == Enter debugger
797 * 0 == [the default] detatch debug client
798 * -1 == Do nothing... and use this until the board resets
800 switch (kgdbreboot) {
812 static struct notifier_block dbg_reboot_notifier = {
813 .notifier_call = dbg_notify_reboot,
818 static void kgdb_register_callbacks(void)
820 if (!kgdb_io_module_registered) {
821 kgdb_io_module_registered = 1;
825 register_reboot_notifier(&dbg_reboot_notifier);
826 atomic_notifier_chain_register(&panic_notifier_list,
827 &kgdb_panic_event_nb);
828 #ifdef CONFIG_MAGIC_SYSRQ
829 register_sysrq_key('g', &sysrq_dbg_op);
831 if (kgdb_use_con && !kgdb_con_registered) {
832 register_console(&kgdbcons);
833 kgdb_con_registered = 1;
838 static void kgdb_unregister_callbacks(void)
841 * When this routine is called KGDB should unregister from the
842 * panic handler and clean up, making sure it is not handling any
843 * break exceptions at the time.
845 if (kgdb_io_module_registered) {
846 kgdb_io_module_registered = 0;
847 unregister_reboot_notifier(&dbg_reboot_notifier);
848 atomic_notifier_chain_unregister(&panic_notifier_list,
849 &kgdb_panic_event_nb);
851 #ifdef CONFIG_MAGIC_SYSRQ
852 unregister_sysrq_key('g', &sysrq_dbg_op);
854 if (kgdb_con_registered) {
855 unregister_console(&kgdbcons);
856 kgdb_con_registered = 0;
862 * There are times a tasklet needs to be used vs a compiled in
863 * break point so as to cause an exception outside a kgdb I/O module,
864 * such as is the case with kgdboe, where calling a breakpoint in the
865 * I/O driver itself would be fatal.
867 static void kgdb_tasklet_bpt(unsigned long ing)
870 atomic_set(&kgdb_break_tasklet_var, 0);
873 static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0);
875 void kgdb_schedule_breakpoint(void)
877 if (atomic_read(&kgdb_break_tasklet_var) ||
878 atomic_read(&kgdb_active) != -1 ||
879 atomic_read(&kgdb_setting_breakpoint))
881 atomic_inc(&kgdb_break_tasklet_var);
882 tasklet_schedule(&kgdb_tasklet_breakpoint);
884 EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint);
886 static void kgdb_initial_breakpoint(void)
890 printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
895 * kgdb_register_io_module - register KGDB IO module
896 * @new_dbg_io_ops: the io ops vector
898 * Register it with the KGDB core.
900 int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops)
904 spin_lock(&kgdb_registration_lock);
907 spin_unlock(&kgdb_registration_lock);
909 printk(KERN_ERR "kgdb: Another I/O driver is already "
910 "registered with KGDB.\n");
914 if (new_dbg_io_ops->init) {
915 err = new_dbg_io_ops->init();
917 spin_unlock(&kgdb_registration_lock);
922 dbg_io_ops = new_dbg_io_ops;
924 spin_unlock(&kgdb_registration_lock);
926 printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
927 new_dbg_io_ops->name);
930 kgdb_register_callbacks();
933 kgdb_initial_breakpoint();
937 EXPORT_SYMBOL_GPL(kgdb_register_io_module);
940 * kkgdb_unregister_io_module - unregister KGDB IO module
941 * @old_dbg_io_ops: the io ops vector
943 * Unregister it with the KGDB core.
945 void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops)
947 BUG_ON(kgdb_connected);
950 * KGDB is no longer able to communicate out, so
951 * unregister our callbacks and reset state.
953 kgdb_unregister_callbacks();
955 spin_lock(&kgdb_registration_lock);
957 WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops);
960 spin_unlock(&kgdb_registration_lock);
963 "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
964 old_dbg_io_ops->name);
966 EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
968 int dbg_io_get_char(void)
970 int ret = dbg_io_ops->read_char();
971 if (ret == NO_POLL_CHAR)
981 * kgdb_breakpoint - generate breakpoint exception
983 * This function will generate a breakpoint exception. It is used at the
984 * beginning of a program to sync up with a debugger and can be used
985 * otherwise as a quick means to stop program execution and "break" into
988 void kgdb_breakpoint(void)
990 atomic_inc(&kgdb_setting_breakpoint);
991 wmb(); /* Sync point before breakpoint */
992 arch_kgdb_breakpoint();
993 wmb(); /* Sync point after breakpoint */
994 atomic_dec(&kgdb_setting_breakpoint);
996 EXPORT_SYMBOL_GPL(kgdb_breakpoint);
998 static int __init opt_kgdb_wait(char *str)
1000 kgdb_break_asap = 1;
1002 kdb_init(KDB_INIT_EARLY);
1003 if (kgdb_io_module_registered)
1004 kgdb_initial_breakpoint();
1009 early_param("kgdbwait", opt_kgdb_wait);